1. Field of the Invention
The present invention relates to the field of high security locks and related security devices.
2. Prior Art
High security locks and similar security devices of various kinds are well-known in the prior art. One type of such lock of particular interest to the present invention is keyboard operated locks wherein users of the locks are provided a code which, when entered into the keyboard, will operate the same. Such codes may be lock dependent, essentially serving as a combination for the lock, may be user dependent, essentially identifying the user to the lock system, or may be a combination of lock and user dependent. An example of the first type of lock are locks controlling access to parts of a secure facility, whereas locks of the second type include those used as part of an automatic teller machine to enable function keys which allow one to withdraw money and conduct other transactions. In that regard, the words lock, locks and security devices as used herein are used in a general sense to denote a means for granting access to a place or enabling a function or an action which is otherwise disabled, such as the operation of a door latch or the withdrawal of funds in an automatic teller machine or other services, communication devices, computing devices, cash machines, point of sale terminals, etc., or alternatively, the disabling of something which is normally enabled, such as might be required to lock or disable something normally left unlocked or enabled.
In a conventional keyboard operated lock, the level of security attained is relatively low because the number to key assignments are fixed and ordered, and the sequence of key depressions of a user are normally observable from either side of the user without substantial difficulty. To alleviate this problem and enhance the security of the overall system, keyboards are known wherein the keys are not given a predetermined and ordered 1-2-3 type sequence, but rather are given identifications Just prior to use which identifications are effectively scrambled before the next such use. In this manner the physical key depression sequence observed during one operation of the system will have no meaning during the next operation of the system when the keys are identified differently. Further, in such systems the key identifications appearing when the user is standing in front of the keyboard are highly directional, and not observable from the side. Thus, the body of the user blocks the key identifications from view by others, so that while the physical key depressions can be observed from the side, the key identifications associated therewith cannot similarly be determined. Apparatus of this general type is disclosed in U.S. Pat. Nos. 4,644,326, 4,479,112, 4,333,090 and 4,502,048. Also, another device having security features which include physical screening as well as mechanical and electronic realignment of numeric key entry functions is disclosed in U.S. Pat. No. 4,032,931.
Apparatus of the foregoing type provides a high level of security, as no information concerning the code for operating the lock, which may be personal to a specific user, is conveyed to an interloper watching the sequence of key depressions used to operate the security device unless the interloper could somehow simultaneously view and record or memorize the code element pattern being displayed in association with the keys. However, such a security device is relatively expensive, primarily because of the mechanical complexity of the manually operable keys, the preferred positioning of each display device for the code elements behind each key, and the structure for reliably and substantially completely limiting the viewability of the display to the user. Such a security device can exhibit less than maximum reliability because of the mechanical nature of the basic input to the device. The keyboard, requiring manual operation, is quite limited regarding minimum allowable size because of the need for a user, perhaps a large man, to conveniently depress one key at a time with his finger. Also the keyboard, used by all persons, may be considered by some to be unacceptably unsanitary, and of course, because of the basic mechanical input requirements thereto, cannot be operated by one having their hands full without setting things down to operate the security device. Furthermore, a person with a physical disability affecting the use of their digits or without digits or hands cannot use such a device.
Thus, it would be desirable to provide a new security device which would maintain or even enhance the level of security achieved by the hereinbefore described devices, but in a manner eliminating the mechanical complexity and resulting lower reliability thereof while at the same time allowing for a smaller and substantially less expensive security device.